The invention relates to a flexible coupling element or joint disc (which latter term is used herein for convenience) made of laminations of a fiber composite material and comprising an even number of angular fixing elements spaced about the disc and a plurality of flexible leaf elements extending circumferentially therebetween.
The leaf elements may be straight so the disc is generally in the form of a polygon. In a basic design of joint discs of the aforesaid type, it is made of superimposed laminations which, in outline, each extend over one leaf element and two adjoining fixing elements. Layering a plurality of said leaf elements in the shape of a polygon thus leads to fixing elements of double thickness relative to the leaf elements because the former contain double the number of superimposed laminations as compared to the latter. The laminations comprising fabric impregnated with resin, each have a main fiber orientation which may vary between the individual laminations. In the central layers of laminations within the leaf elements the main fiber orientation may coincide with the longitudinal direction of the laminations, whereas the outer layers may comprise alternately opposed angles of intersection of the main fibre orientation relative to the longitudinal direction of the leaf element.
Joint discs or shaft coupling elements of this type used for connecting two shafts and suitable for relatively limited angles of articulation between the shafts are known from DE-3725957-C1 and DE-4033596-C1. Flange parts of the two shafts be coupled are circumferentially alternately bolted to the fixing elements of the joint disc, which are provided with bolt holes. Whereas the fixing elements and reinforced eye regions thereof around the bolt holes respectively can be regarded as substantially rigid, the leaf elements or web regions therebetween, in the case of shafts articulated relative to one another, are bent in the form of an S-wave on which are superimposed forces due to torsion. To reduce load peaks the former publication DE-3725957-C1 already proposes to provide the transition between the web regions and eye region with radii; in DE-4033596-C1 it is proposed--again in order to reduce load peaks--to position the fixing holes radially inwardly with reference to the longitudinal center lines of the web region. Furthermore, the previously mentioned shaft coupling elements are limited to relatively small operating angles. An important factor continues to be load peaks in the case of shafts which are angled relative to one another, i.e. load peaks in the regions of transition between leaf elements and fixing elements.
It is therefore the object of the present invention to improve a joint disc of the initially mentioned type in such a way as to permit larger operating angles when using a joint disc of a predetermined size, i.e. of a certain diameter.